Pharmacokinetics, biodistribution, stability and toxicity of a cell-penetrating peptide-morpholino oligomer conjugate.

Objective: Conjugation of arginine-rich cell-penetrating peptide (CPP) to phosphorodiamidate morpholino oligomers (PMO) has been shown to enhance cytosolic and nuclear delivery of PMO. However, the in vivo disposition of CPP-PMO is largely unknown. In this study, we investigated the pharmacokinetics, tissue distribution, stability, and safety profile of an anti-c-myc PMO conjugated to the CPP, (RXR)4 (X = 6-aminohexanoic acid) in rats.

Reduction in tamoxifen-induced CYP3A2 expression and DNA adducts using antisense technology.

Tamoxifen (TAM) is widely used in the treatment and prevention of breast cancer. There is clear evidence that cytochrome P450 (CYP) 3A enzymes play an important role in TAM metabolism, resulting in metabolites that lead to formation of TAM-DNA adducts. We have investigated the effect of CYP3A2 antisense (AVI-4472) exposure on CYP3A2 transcription, enzyme activity, translation, and TAM-DNA adducts, in livers of rats administered TAM (50 mg/kg body weight [bw]/day) for 7 days.

Phosphorodiamidate morpholino antisense oligomers inhibit expression of human cytochrome P450 3A4 and alter selected drug metabolism.

Antisense phosphorodiamidate morpholino oligomers (PMO) inhibit targeted gene expression by preventing ribosomal assembly, thus preventing translation. Inhibition of cytochrome P450 (P450) 3A4 expression was examined in primary human hepatocytes from 11 donors and in Caco-2 cells (stably transfected with CYP3A4 cDNA on an extrachromosomal vector) by evaluating the metabolism of substrate 7-benzyloxy-4-[trifluoromethyl]-coumarin and Western immunoblot analysis. Cellular uptake of PMO was confirmed in both cell systems using fluorescein-labeled PMOs.